Preparation of film via a tubular process

ABSTRACT

AN IMPROVED METHOD OF PREPARING FILMS OF HIGHLY VISCOUS HYDROXYPROPLY CELLULOSE TO MINIMIZE THE EFFECT OF FRICTION-INDUCED LONGITUDINAL ORIENTATION ON LATER BALANCING OF LONGITUDINAL AND TRANSVERSE ORIENTATION IS DISCLOSED. THE TECHNIQUES COMPRISES SUBJECTING THE FILM TO A TRANSVERSE FRICTIONAL DRAG DURING EXTRUSION BY EXTRUDING THE POLYMER THRU A TUBULAR DIE HAVING ROTATABLE FORMING SURFACES, I.E. DIE BODY AND MANDREL. THE RATE OF ROTATION CAN BE VARIED TO EFFECT A SUBSTANTIALLY BALANCED DEGREE OF FRICTION-INDUCED ORIENTATION OR A PREPONDERANCE OF ORIENTATION IN THE CIRCUMFERENTIAL DIRECTION. AN ANCILLARY BENEFIT IS THAT THE ROTATION SUBSTANTIALLY WIPES OUT WELD LINES   FORMED BY THE POLYMER FLOWING AROUND THE MANDREL SUPPORT.

DEFNSWE PUBLIGATIUN UNITED STATES PATENT OFFICE Published at the requestof the applicant or owner in accordance with the Notice of Dec. 16,1969, 869 O.G. 687. The abstracts 01 Defensive Publication applicationsare identified by distinctly numbered series and are arrangedchronologically. The heading of each abstract indicates the number ofpages of specification, including claims and sheets of drawingscontained in the application as originally filed. The files of theseapplications are available to the public for inspection and reproductionmay be purchased for 30 cents a sheet.

Defensive Publication applications have not been examined as to themerits of alleged invention. The Patent Oiiice makes no assertion as tothe novelty of the disclosed subject matter.

PUBLISHED APRIL 3, 1973 T909,ll07 PREPARATION 0F FILM VIA A TUBULARPROCESS Paul E. Holloway, In, New Castle, Del., assignor to Herculesincorporated, Wilmington, Del. Filed June 6, 1972, Ser. No. 260,228lint. Cl. B291: 5/05, 23/00; B29d 7/22 U.S. (Tl. 264-95 1 Sheet Drawing.6 Pages Specification An improved method of preparing films of highlyviscous hydroxypropyl cellulose to minimize the effect offriction-induced longitudinal orientation on later balancing oflongitudinal and transverse orientation is disclosed. The techniquecomprises subjecting the film to a transverse frictional drag duringextrusion by extruding the polymer thru a tubular die having rotatableforming surfaces, i.e. die body and mandrel. The rate of rotation can bevaried to cflcct a substantially balanced degree of friction-inducedorientation or a preponderance of orientation in the circumferentialdirection. An ancillary benefit is that the rotation substantially wipesout weld lines formed by the polymer flowing around the mandrel support.

April 1973 p, HOLLOWAY. JR T909,007

PREPARATION OF FILM VIA A TUBULAR PROCESS Filed June 6, 1972 2 II I IIII I! ll I II,/ II I!

